/Engine/Source/Editor/BlueprintGraph/Classes/K2Node_DynamicCast.h
true, is pins cannot be connected due to node's inner logic, put message for user in OutReason
virtual bool IsConnectionDisallowed ( const [UEdGraphPin](API\Runtime\Engine\EdGraph\UEdGraphPin) * MyPin, const [UEdGraphPin](API\Runtime\Engine\EdGraph\UEdGraphPin) * OtherPin, [FString](API\Runtime\Core\Containers\FString) & OutReason ) const